1. Field of the Invention
The invention relates to an image processing apparatus for reconstructing a deteriorated image.
2. Description of the Related Art
Hitherto, in the case where an object was photographed by an image pickup apparatus such as a digital camera, there is a situation where when the image is seen later, it becomes a deteriorated image due to an out-of-focus or the like. In such a case, a trial to reconstruct the deteriorated image by a super resolution process is made and various kinds of algorithms for the super resolution are considered. For example, Irani and Peleg propose a typical method (hereafter “Irani-Peleg method”) for reconstruction from a plurality of blur images in Improving Resolution by Image Registration CVGIP: GRAPHICAL MODELS AND IMAGE PROCESSING Vol. 53, No. 3, pp. 231-239, May 1991.
The following equation (1) is used in an image reconstructing process of the Irani-Peleg method. According to such a system, an unknown original image is gradually presumed from the deteriorated image in a repetitive process. At this time, a norm (differential square sum of each pixel) of a pseudo blur image g(n) formed by convolving a point spread function (hPSF) showing a presumed blur to a just-previous reconstruction image f(n) shown in the equation (1) and a blur image g obtained by photographing is calculated and it is assumed to be f(n+1). That is, e(n) in the following equation (2) is calculated and a case where it is minimum is regarded as completion of the image reconstruction.
                                                                        f                                  (                                      n                    +                    1                                    )                                            =                                                f                                      (                    n                    )                                                  +                                                      (                                          g                      -                                              g                                                  (                          n                          )                                                                                      )                                    ×                                                            h                      AUX                                        /                    c                                                                                                                          =                                                f                                      (                    n                    )                                                  +                                                      (                                          g                      -                                                                        f                                                      (                            n                            )                                                                          ×                                                  h                          PSF                                                                                      )                                    ×                                                            h                      AUX                                        /                    c                                                                                                          Equation        ⁢                                  ⁢                  (          1          )                    
where,                c: normalization constant        ω: spatial frequency        
hAUX may be a function which satisfies0<|1−HPSF(ω)·HAUX(ω)/c|<1
with respect to all ω and HPSF is generally used.                H: Fourier transformation of he(n)=∥g(n)−g(0)∥  Equation (2)        where, ∥ ∥: norm showing the differential square sum or differential absolute value sum of each pixel.        
An algorithm obtained by improving a typical Richardson-Lucy method using a Bayes presumption for a presumption of an original image has been disclosed in Japanese Patent Application Laid-Open No. 2006-242746. Fifteen kinds of non-patent documents regarding the super resolution process have been disclosed in Japanese Patent Application Laid-Open No. 2006-195856.
A technique for measuring a distance to an object to be photographed and obtaining distance information of each pixel is also known. For example, a method called a stereo method of improving distance measuring precision at a far distance by combining a telescope to a technique for measuring a distance to an object to be photographed has been disclosed in Japanese Patent Application Laid-Open No. H11-257951.